Re-writable non-volatile memory is used for various purposes mainly related to persistent data storage with possibility of modification. Practical applications of re-writable non-volatile memory include storage of digital pictures, computer files, digitally recorded music and so on. Thus, it is common to find re-writable non-volatile memory in everyday electronic devices such as computers, digital cameras, MP3 players, answering machines, cell phones, etc.
There are many ways in which data can be physically stored by a non-volatile memory device that also allows re-writing. One example is by using a magnetic disk as can be found in many computer hard drives. Another example is by way of an optical disk such as a CD-R/W. Yet another example is by means of a solid state memory circuit such as an electrically erasable and programmable read-only memory (EEPROM), a specific example of which is a flash memory device. A flash memory device utilizes a high voltage to erase a large block of non-volatile memory cells in one operation, allowing these cells to then be reprogrammed with new data. By virtue of their robustness, convenience and low cost, flash memory devices have gained immense popularity in the marketplace for non-volatile memory and are expected to become even more dominant as the demand for non-volatile memory continues to grow unabated.
In the years since flash memory was first introduced, technological refinements have been made in order to allow flash memory devices to be operated at increasingly higher speeds. This has further expanded the breadth of consumer applications in which flash memory devices can be used to include, for example, certain video and photo related applications. However, faster operation of a flash memory device can also lead to specific problems when attempting to create a large high-speed memory system. In particular, the electrical power consumption of a flash memory device, which increases with operating frequency, can significantly limit the practically attainable capacity of the memory system.
Against this background, there is clearly a need for a non-volatile memory device with reduced power consumption.